Water circulation systems for ponds, lakes, and other bodies of water

ABSTRACT

Circulation systems for ponds, lakes, or other bodies of water. In one set of embodiments, water is drawn up from the depths of the body for exposure to the atmosphere and to generate an overall, high flow circulation pattern throughout the entire body. In other embodiments, the circulation in the body of water is primarily limited to an upper aerobic zone with only small and controlled volumes from a lower anaerobic zone being brought up. Each system preferably includes a flotation platform, dish, impeller, and draft tube with specific modifications to the various systems to adapt them for use in a variety of environments.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.11/848,425 filed Aug. 31, 2007, which is a division of U.S. patentapplication Ser. No. 10/749,064 filed Dec. 30, 2003, now U.S. Pat. No.7,285,208 issued Oct. 23, 2007, which claims the benefit of U.S.Provisional Patent Application Ser. No. 60/437,217 filed Dec. 31, 2002,all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of circulation systems for ponds,lakes and other bodies of water and more particularly to the field ofsuch circulation systems for relatively large and deep bodies of waterthat require fairly high flow rates to be most effective and systems forsmaller bodies such as municipal wastewater ponds that are designedprimarily for treating domestic and industrial wastes and have specialrequirements to be effective.

2. Discussion of the Background

In regard to larger and deeper bodies of water that require high flowrates to be most effective, the fundamental goal of such systems is tocreate a nearly laminar surface flow out to the edges of the pond whileuplifting water from the bottom depths of the pond. In doing so, theoxygen depleted water from the bottom depths is exposed to and absorbsoxygen from the atmosphere while undesirable gases such as hydrogensulfide are passed off into the atmosphere. Additionally, an overallcirculation pattern is generated in the pond that mixes the reaeratedwater throughout the entire pond. Such mixing in turn accelerates thebiological and solar processes that clean up the water. The resultingcleansing is particularly desirable as it relates to controlling orremoving weed growth, algae bloom, sludge buildup, fish kills, odors,high amounts of nitrogen and phosphorus, acidity, suspended solids, andother conditions.

Power availability to run the pump or impeller of the circulation systemand seasonal weather conditions (e.g., surface ice) present great designchallenges for optimum performance. Remote ponds or other bodies ofwater can be a particular challenge as the only available power sourcemay be solar energy. Yet, the impeller of the system preferably will beable to lift and induce the flow of relatively large volumes of waterfrom relatively large depths, as for example 30 to 50 or more feet.Further, the upflow or lifting must be done in a manner that spreads thewater gently and evenly across the surface of the pond in a nearlylaminar flow pattern. Otherwise, the overall flow and mixing of theuplifted water will not reach the edges of the pond and will simply beconcentrated in the immediate area of the impeller leaving the outerreaches of the pond stagnant and untreated.

In a well designed system as indicated above, the surface of the pondwould be continually renewed with water drawn up from the bottom depthswhile maintaining a laminar surface flow out to the edges of the pond.The surface water will then absorb oxygen from the atmosphere whileundesirable gases such as hydrogen sulfide pass out of the water intothe atmosphere. Among other beneficial actions, such surface reaerationand subsequent mixing and diffusion of the aerated water throughout thedepths of the pond will increase desirable aerobic activity. It willalso reduce suspended and dissolved solids in the water increasing pondclarity and aiding sunlight penetration and heat transfer for furthercleaning.

In circulation systems for smaller bodies of water such as municipalwastewater ponds for treating domestic and industrial wastes, the highflow circulation pattern throughout the entire body of water discussedabove is not always effective to process the wastes and in some casescan be counterproductive. One problem in such smaller ponds (e.g., 5 to15 feet deep) is that the domestic and commercial wastes are usuallymuch stronger and more concentrated. Also, such municipal wastewaterponds rely on more complicated mechanisms including biological andchemical ones for treating and processing the waste. These mechanismsinvolve the establishment of an upper, aerobic zone and a lower,anaerobic zone. Each zone is essential for the proper and overalltreatment and processing of the various and different waste materialsand each zone has its own biological and chemical needs that are oftenthe opposite of the other and often detrimental to the other.Consequently, any thorough and overall mixing of the entire pond as inthe earlier high flow systems for larger bodies of water will normallydestroy the two zones and the effectiveness of the wastewater treatmentpond.

With these and other considerations in mind, the water circulationsystems of the present invention were developed.

SUMMARY OF THE INVENTION

In one set of embodiments of the present invention that are primarilydesigned for larger and deeper bodies of water, a high flow circulationsystem is disclosed. The high flow system draws water up from the depthsof a pond, lake, or other body of water for exposure to the atmosphereand generates a desirable, overall circulation pattern throughout theentire body of water. The system includes a flotation platform, dish,impeller, and draft tube depending from an annular housing. The dish issupported just below the surface of the water and the bottom of the dishis spaced from the top of the housing to create an annular opening.

In operation, water from the depths of the pond is uplifted by theimpeller through the draft tube toward the housing and dish. In doing soand in the preferred manner of use, the uplifted water passes out notonly up over the upper edge of the dish but also out the annular openingbetween the housing and the dish. Preferably, about ⅔rds of the volumeof the uplifted water passes out the annular opening and ⅓rd continuesupwardly into and out of the dish. With this design, a significantlyhigher flow rate can be handled by the system without creatingundesirable turbulent flow at the surface of the pond or other body ofwater.

The impeller preferably includes two, half blades with diameters lessthan the diameters of the housing and the bottom of the dish. In thismanner, a gap is created between the blades and the housing as well asthe dish which generates less turbulence in the uplifted water. Thesmaller diameters also permit the vertical positioning of the impellerblades relative to the dish and housing to be adjusted. This adjustmentin turn allows the proportions of the uplifted water discharged throughthe annular opening and over the top of the dish to be varied asdesired.

The draft tube is specially constructed to have a neutral or slightlypositive buoyancy and a cable arrangement is provided to selectivelyadjust the extended length and depth of the collapsible tube. The cablearrangement includes a spring to aid in protecting the main cable andtube from damage from the uplifting forces of surface waves on theflotation platform. Additionally, the arrangement includes a shortlength of cable positioned adjacent the spring which limits the maximumextension of the spring and overall cable arrangement to protect thedraft tube from being stretched beyond its design limits. An electroniceutrophication control system can also included to create apatite fromcalcium and phosphate molecules present in the water.

In the set of embodiments specifically intended for use in relativelysmall (e.g., 5 acres) and shallow (e.g., 5 to 15 feet) municipalwastewater ponds, many of the structural features of the high flowsystems are used but their operation is modified. As for example, theimpeller is still used to create a laminar flow pattern out to the edgesof the pond but instead of having the draft tube draw up relativelylarge volumes of water from adjacent the bottom of the pond, only a verysmall or metered amount is drawn up. The circulation path of the watercreated by the impeller is then concentrated and preferably limited tothe upper aerobic zone (e.g., top 2 feet of the pond). In this upperzone, the circulating and aerating of the flow are most beneficial andadvantageous to the biological and chemical actions of the upper zone.The lower anaerobic zone (e.g., bottom 2 feet of the pond) is thenessentially left alone and unaffected by the circulating flowestablished in the upper zone. The proper environment for the desirablebiological and chemical actions of the lower zone is then not destroyed(e.g., by introducing dissolved oxygen from the upper zone into thelower one). Similarly and because the upper and lower zones aresubstantially isolated from one another, the biological and chemicalactions of the upper zone are not detrimentally harmed by beingthoroughly mixed as in the high flow systems. Nevertheless, it is stilldesirable for the overall treatment of the wastewater in the pond tobring up and mix very small volumes from the lower zone into the upperzone. In the second set of embodiments, this is accomplished bystructure and its operation in a very careful and controlled manner.

Other features and modifications to the parts and operation of thecirculating systems of the present invention are also disclosed to adaptthem for use in additional environments and situations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the circulation system of a firstset of embodiments of the present invention in use to create an overallflow pattern out to the edges and down to the depths of the pond orother body of water.

FIG. 2 is an enlarged view of the flotation platform of the system.

FIG. 3 is simplified, top plan view taken generally along line 3-3 ofFIG. 2 showing the flotation platform and the laminar surface flowcreated circumferentially about the dish of the present invention.

FIG. 4 is a view taken along line 4-4 of FIG. 3 illustrating the detailsof the flotation platform including the annular opening between thebottom of the dish and the top of the housing attached to the drafttube.

FIG. 5 is a perspective view of the dish and housing of the presentinvention showing the annular opening created between them.

FIG. 6 is a perspective view similar to FIG. 5 but additionally showingthe preferred positioning of the impeller blades relative to the dishand housing.

FIG. 7 is a view similar to FIG. 4 with the impeller blades shown in alowered position and further illustrating the cable arrangement forcontrolling the depth of the draft tube and protecting the main cableand tube from damage due to surface waves.

FIG. 8 is a view taken along line 8-8 of FIG. 7.

FIG. 9 illustrates the operation of a safety feature of the cablearrangement wherein the spring of FIG. 7 expands to absorb the upliftingforce of a surface wave on the flotation platform and protect the maincable from damage.

FIG. 10 illustrates the operation of the short length of safety cableadjacent the spring to protect the spring and more importantly the tubefrom being stretched beyond their design limits.

FIG. 11 schematically illustrates the circulation system of the presentinvention adapted to include an electronic eutrophication control systemto create apatite from any calcium and phosphate molecules present inthe water.

FIG. 12 schematically illustrates the preferred operation of another setof embodiments of the present invention in which an upper aerobic zoneand a lower anaerobic zone are created and maintained in a wastewaterpond.

FIGS. 13 and 14 schematically illustrate difficulties in setting theproper depth of the inlet to the draft tube of circulating systems likethose of FIG. 1 in the environment of a wastewater treatment pond inwhich it is desirable to have both aerobic and anaerobic zones.

FIG. 15 illustrated the overall structure of the preferred embodiment tocreate the desired circulation system of FIG. 12.

FIG. 16 is a view taken along line 16-16 of FIG. 15.

FIG. 16 a is an enlarged view of a portion of FIG. 16.

FIG. 17 is a perspective view of the dish, impeller, housing, and platemember of the circulating system of FIG. 15.

FIG. 18 is a cut away view of FIG. 17.

FIG. 19 is view similar to FIG. 15 illustrating the various flow pathscreated in the system.

FIG. 20 is a side elevation view of the upper part of the system.

FIG. 21 illustrates the upper part of the system in an adjustedposition.

FIG. 22 shows the application of the second set of embodiments to treata series of bodies of wastewater.

FIG. 23 is an enlarged view of the inlet portion of the draft tube ofthe embodiment of FIG. 1 modified to allow a controlled amount of waterto be drawn up through the bottom plate member thereof.

FIG. 24 show the use of the embodiment of FIG. 23 in the environment ofa canal.

FIGS. 25 and 26 illustrate further modifications to the inlet portion ofthe embodiment of FIG. 1 adapting it to be supported on the bottom of amunicipal water tank and provided with vertically extending arm membersto collect and contain the collapsing draft tube as the water level inthe tank drops.

FIG. 27 schematically illustrates another embodiment of the presentinvention adapted for use to create an odor cap in a waste tank.

DETAILED DESCRIPTION OF THE INVENTION

As schematically shown in FIG. 1, the water circulation system 1 of afirst set of embodiments of the present invention includes an upperflotation platform 3 with a draft hose or tube 5 depending downwardlyfrom it to the water inlet 7. The inlet 7 is preferably positionedadjacent and slightly raised from the bottom 2 of the pond or other bodyof water 4. The flotation platform 3 as best seen in FIGS. 2 and 3includes three floats 9 supported on the tubular frame 11 of theplatform. The floats 9 extend outwardly of the central axis 13 and arepreferably evenly spaced about the axis 13 (see FIG. 3). The floats 9extend far enough out from the central axis 13 to provide a relativestable and buoyant support structure for the system 1 including itssolar panels 15, electric motor 17, dish 19 (see also FIGS. 4 and 5),impeller 21 (see also FIGS. 4 and 6), draft hose 5, and the water inlet7 of FIG. 1. As explained in more detail below, the draft hose 5 is alsospecially designed to be essentially neutrally or slightly buoyant overits length, further adding to the stability of the system 1.

The overall buoyancy of the system 1 and in particular the platform 3 ispreferably designed to support the upper edge or lip 19′ (see FIG. 4) ofthe dish 19 about 3 inches or so below the surface 6 of the pond orother body of water 4. Additionally, as perhaps best seen in FIG. 4, thebottom edge 19″ of the dish 19 is spaced (e.g., 1.5 inches) from theupper edge 25′ of the housing 25 to create an annular opening 27extending about the axis 13 (see also FIG. 5). Spacers 29 as illustratedin FIG. 5 support the dish 19 and housing 25 apart to create the opening27. The spacers 29 preferably are as few and small as possible so thatthe opening 27 extends substantially continuously and completely aboutthe central axis 13. Preferably, the total amount of the opening 27 isat least 320 degrees or higher about the axis 13 with the spacers 29then obscuring only a relatively small amount of the remaining 360degrees.

As explained in more detail below, the impeller 21 is verticallyadjustable along the axis 13. However, in the preferred positioning ofFIGS. 4 and 6, the two cross blades 31 of the impeller 21 aresymmetrically centered with half of each blade 31 above and below thehorizontal plane of the lower dish edge 19″, (see FIG. 4). In thisregards the diameter of the dish 19 at the top or upper edge 19′ isabout 6 feet. The dish 19 itself is approximately 6 inches deep andslopes downwardly and inwardly to the bottom or lower edge 19″, whichhas a diameter of about 30 inches. The blades 31 of the impeller 21 arepreferably about 27 inches across with the outer edges or tips beingvertically spaced from each other about 4 inches. Each half blade 31 isinclined to the vertical axis 13 at about 15 degrees. The annularhousing 25 in FIG. 4 (which essentially forms the upper end portion oroutlet for the flexible draft tube 5) is approximately 30 inches indiameter. The housing 25 has an outwardly extending flange 35 (see FIG.4) to which the depending flange 37 is affixed. The diameter of thedepending flange 37 is about 36 inches. The upper rim of the flexibledraft hose 5 (see FIG. 4) then extends about the depending flange 37 andis secured thereto by a band clamp 39.

In operation as best seen in FIGS. 1 and 4, the impeller 21 (FIG. 4) isrotated about the axis 13 to draw water into the bottom inlet 7 (FIG.1). The water is then uplifted through the draft hose 5 toward thehousing 25 and dish 19. In doing so and in the preferred manner ofoperation, the volume of uplifted water (represented schematically byarrow 8 in FIG. 4) passes out not only up over the upper edge 19′ of thedish 19 but also out the annular opening 27 between the housing 25 andthe dish 19. Preferably, about ⅔rds of the volume of the uplifted water8 passes out the annular opening 27 (schematically represented by arrows10) and ⅓rd continues upwardly into and out of the dish 19 (see arrows12). The uplifted water 8 in FIG. 4 is then discharged both below andabove the dish 19.

In this last regard, it was discovered in using water circulationsystems such as those of U.S. Pat. Nos. 6,433,302 and 6,439,853 (whichare incorporated herein by reference) that significantly higher flowrates were needed to treat larger and deeper bodies of water. However,when the flow rates of the prior designs were increased, the surfacedischarge from the dish became undesirably turbulent. That is, when theflow rate was increased (e.g., from 450 gallons per minute to 3000) inorder to generate the desired circulation pattern of FIG. 1 in largerand deeper bodies of water (e.g., 300 acres at 30 feet versus 30 acresat 12 feet), the surface discharge of FIG. 3 from the 6 foot dish of theprior designs no longer remained laminar. Consequently, the turbulentsurface flow outwardly of the top of the dish only carried out to coverabout a 5 acre circle (versus the normal 30 acre circle of such deviceswith the lesser but laminar surface flow). Lowering the upper edge ofthe dish more than 1 inch below the water surface of these prior devicesdid not help as the surface flow was still turbulent at the higher flowrates. It was contemplated to use a larger dish (e.g., 18 foot diameterversus 6) but this was not commercially feasible for manufacturing andshipping reasons. It was then discovered that by providing an annularopening 27 between the bottom of the dish 19 and the top of the housing25, the circulation system 1 of the present invention could handlesignificantly larger flow rates (volumes) without creating undesirablesurface turbulence. Further, the system 1 could do so still using only arelative small (e.g., 6 foot) dish 19. The increased flow rateadditionally induced much larger flows 14 (see FIG. 1) along the outsideof the draft tube 5 further enhancing the ability of the presentinvention to treat much larger and deeper bodies of water than the priordevices. Even in smaller and shallower ponds that previously used aplurality of the prior devices for complete treatment, the presentdesign was more efficient as fewer of them were needed to accomplish thesame results. In most cases, a single system of the present design couldreplace four to six of the prior designs.

It is noted that in the prior systems of U.S. Pat. Nos. 6,433,302 and6,439,853, their impellers were positioned completely in the dish abovethe plane of the lower edge of the dish. Further, the blades of theirimpellers extended outwardly beyond the diameter of the lower edge ofthe dish as well as the diameters of the housing and draft tube belowit. The positioning of the impeller and its blades in this regard waslimited to being in the dish. In contrast, the blades 31 of the impeller21 of the present invention have diameters (e.g., 27 inches) less thanthe diameter (e.g., 30 inches) of the lower dish edge 19″, and thehousing 25 below it. Consequently, there is a 1.5 inch annular gap orspacing between the outer diameter of the blades 31 and thecircumferences of the lower dish edge 19″ and the housing 25.Additionally, each blade 31 as discussed above is preferably positionedhalf above and half below the horizontal plane of the lower dish edge19″ (see FIGS. 4 and 6). By so dimensioning the diameters of the blades31 to be smaller and positioning the blades 31 as discussed above, itwas discovered that the blades 31 could lift a significantly highervolume of water than those of the prior devices (e.g., 3000 gallons perminute versus 450). Additionally, this could be done running the blades31 at lower revolutions per minute than in the prior devices (e.g., 100versus 150) and using less wattage (e.g., 80 watts versus 96). In termsof gallons per minute of flow per watt of energy used, the gain overprior devices was about 800 or more percent (e.g., 35 gpm/watt versus4-4.5).

This performance improvement is believed to be due in part to areduction in the turbulence and bounce back of the water outwardlyagainst the housing 25 and draft tube 5 as the water is being upliftedby the impeller 21. Similarly, it is believed that with the gap versus apositive displacement arrangement, the lifting effect of the blades 21induces a less turbulent flow along the walls of the draft tube 5. Inthis regard, the blades 31 (with 27 inch diameters as projected on aplane perpendicular to the axis 13 and together extending completelyabout the axis 13) preferably occupy about 80-90 percent of thecross-sectional area of the 30 inch diameter housing 25. The gap is thenbelieved to work in conjunction with the upward water flow through thedraft tube 5 to allow the water coming off the sides of the impeller 21to turn and flow upward instead of tangentially outward and away fromthe center of the impeller 21. In operation and with reduced turbulenceand bounce back, less energy is lost and higher flow rates are achieved.Empirically, it was determined that without the annular gap or spacing,the flow rate dropped 20 percent. The gap together with the slowerrotation of the impeller 21, larger diameter blades 31, and larger pitchor bite of the blades 31 (e.g., 4 inches versus 1) all contribute tosignificantly improving the overall performance of the present systemover prior designs.

The higher flow rate of the present invention additionally enables thedish 19 to be submerged lower below the surface 6 of the water (e.g.,from 1 inch in the prior devices to 3 inches). The advantage of beingable to lower the dish to 3 inches is particularly significant in manylocations in that on a cold night, a 1 inch thick layer of ice caneasily form on the water surface. Consequently, when the sun comes upand the impeller is restarted, the top of the dish of prior deviceswould often be completely plugged by the ice layer and no flow couldpass out over the top of the dish. In an effort to overcome this, verysmall and narrow, radial slits in the dish were provided in the mainbody of the dish of the prior devices. The purpose of these radial slitswas to allow a very limited amount of upward flow of warmer water fromthe bottom of the pond in an effort to melt the ice cap. In normaloperation, no flow would pass through these radial slits and it was onlywhen ice plugged the top of the dish that it would. However, even then,it was not enough in most cases to efficiently melt the ice cap and itwas necessary to wait for the surface conditions (e.g., sun) to improveto melt the ice. In contrast and with the present invention, the dish 19can be submerged lower in the water (e.g., 3 inches versus 1) so that itis less likely an overnight freeze will create a blocking cap. Further,even if it does, the annular opening 27 between the dish 19 and housing25 will permit high volumes of water to pass out (e.g., 80 percent ofthe normal capacity of the impeller 21 or about 2400 gallons perminute). This will create an overall circulation pattern similar to theone of FIG. 1 to begin treating the water. It will also bring upsignificant amounts of the warmer water from the bottom 2 to help meltthe ice cap above the dish 19. The uplifted water will then also beginmelting the surface ice outwardly of the dish 19 to eventually establishthe full surface and subsurface circulation pattern of FIG. 1.

As mentioned above, the impeller 21 of the present invention isvertically adjustable relative to the dish 19 and housing 25 (whichessentially forms the upper end portion or outlet for the draft tube 5).As perhaps best seen in FIG. 7, the electric motor 17 for the impeller21 is mounted on a plate 41 that can be raised or lowered relative tothe frame 11 by rotation of the threaded bolts 43. That is, by rotatingthe bolts 43 relative to the nuts 45 affixed to the plate 41, the plate41 and motor 17 can be raised or lowered as desired. The advantage ofthis adjustability is that the relative proportion of the uplifted water8 in FIG. 4 that passes out the opening 27 versus up and over the dish19 at 12 can be varied. As for example and by lowering the motor 17(including the shaft 47 and attached impeller 21) to the position ofFIG. 7, a higher percentage of the uplifted water in the draft tube 5will pass out the opening 27 than in the raised position of FIG. 4.Conversely, if it is desirable for a particular operating condition tohave more of the uplifted water pass up and out over the top of the dish19, the impeller 21 can be raised toward or beyond the position of FIG.4. As mentioned above, the relative portions of the uplifted waterpassing out the annular opening 27 versus up through and out the topedge 19′ of the dish 19 in FIG. 4 is about 2:1. However, by adjustingthe vertical positioning of the impeller 21, this ratio can be varied asdesired to be higher (e.g., 3:1) or lower (e.g., 1:1).

As briefly mentioned above, the draft hose or tube 5 is preferablydesigned to be neutrally or slightly positively buoyant. It is alsodesigned to be collapsible from an extended length of about 26 feet downto four feet for ease of shipping and handling. Additionally, theextended length of the hose 5 has been made to be adjustable for use inbodies of water of different or varying depths. In this manner, thewater inlet 7 (see FIG. 1) of the hose 5 can then be positioned asdesired relative to the bottom 2 of the body of water 4. The inlet 7 inthis regard essentially forms the lower end portion of the draft tube 5.Preferably, the inlet 7 in most cases does not actually rest on thebottom 2 but is slightly raised (e.g., 3-4 feet) above it. Anotherfeature of the draft hose 5 of the present invention is an arrangementto allow for dampening the effect of surface waves (which in largerbodies of water can often be quite significant) and protecting thestructure of the system 1 from being damaged.

In further reference to the hose 5 of the present invention, theincreased length of the hose 5 for use in deeper bodies of water than inprevious devices presented significant weight and adjustment problems.To overcome the weight problem and to allow for adjustment of theoverall length of the tube 5, the hose 5 was made to be neutrally orslightly positively buoyant and given a collapsible, accordion orbellows design whose collapsible walls extend between the upper andlower end portions of the draft tube or hose 5. The hose buoyancy wasachieved by spirally wrapping styrofoam ribbon into the hose walls alongwith stainless steel wire, fiber, and plastic reinforcements. The slatsof the hose walls in this regard are preferably about 3 inches and willcollapse down from about 26 feet to about four feet. In use asillustrated in FIG. 1 and with the anchor 51 on the bottom 2 of the bodyof water 4, the bellows or accordion-shaped hose 5 is extended under theweight (e.g., 30 pounds) of the inlet 7 to a position just slightlyraised (e.g., 1-4 feet) from the bottom 2. To accomplish this, a steelcable 53 (e.g., ⅜ths inch) is run as shown in FIG. 7 from the reel 55through the bracket 57 and downwardly where the cable 53 is attached bya dampening spring 59 to the inlet 7. The bracket 57 depends from thevertical vane 61 (see FIG. 8) which is mounted across the housing 25 andwhich also supports the lower bearing 63 for the impeller shaft 47. Thevertical vane 61 is positioned below the impeller 21 and also serves tolimit the circular or vortexing flow of the uplifted water in the drafttube 5. In further reference to the hose 5 of the present invention, theincreased length of the hose 5 for use in deeper bodies of water than inprevious devices presented significant weight and adjustment problems.To overcome the weight problem and to allow for adjustment of theoverall length of the tube 5, the hose 5 was made to be neutrally orslightly positively buoyant and given a collapsible, accordion design.The hose buoyancy was achieved by spirally wrapping styrofoam ribboninto the hose walls along with stainless steel wire, fiber, and plasticreinforcements. The slats of the hose walls in this regard arepreferably about 3 inches and will collapse down from about 26 feet toabout four feet. In use as illustrated in FIG. 1 and with the anchor 51on the bottom 2 of the body of water 4, the bellows or accordion-shapedhose 5 is extended under the weight (e.g., 30 pounds) of the inlet 7 toa position just slightly raised (e.g., 1-4 feet) from the bottom 2. Toaccomplish this, a steel cable 53 (e.g., ⅜ths inch) is run as shown inFIG. 7 from the reel 55 through the bracket 57 and downwardly where thecable 53 is attached by a dampening spring 59 to the inlet 7. Thebracket 57 depends from the vertical vane 61 (see FIG. 8) which ismounted across the housing 25 and which also supports the lower bearing63 for the impeller shaft 47. The vertical vane 61 is positioned belowthe impeller 21 and also serves to limit the circular or vortexing flowof the uplifted water in the draft tube 5.

In initial operation to lower the draft tube 5, the locking bolt 65 ofFIG. 7 on the hand crank 67 is first raised. The crank 67 can then berotated about the axis 69 to release enough cable 53 from the reel 55 tolower the inlet 7 and attached tube 5 to the desired depth. This isnormally done by simply lowering the inlet 7 to the bottom 2 and raisingit 1-4 feet or until the flow at the dish 19 has the desired appearancerepresenting the desired depth for best treatment of the water. In somecases, the depth of the bottom 2 may exceed the designed limit (e.g., 26feet) of the hose 5. Consequently, the maximum length of cable on thereel 55 is set accordingly not to exceed this limit.

When used in larger bodies of water, relatively large waves may begenerated by wind or recreational boats raising and lowering theflotation platform 3 several feet or more. To protect the cable 53 andhose 5 from damage from such fluctuations, the cable 53 as illustratedin FIG. 7 is attached to the spring 59. The spring 59 (e.g., ⅜ths inchcoil spring of steel similar to a car body spring) is about 2 feet longin FIG. 7. As the flotation platform 3 in FIG. 7 is raised by a wave,the rising cable 53 will stretch the spring 59 (see FIGS. 9 and 10) toabsorb the lifting force of the wave. This in turn will minimize damageto the cable 53 as well as the hose 5, The action of the spring 59 willthen let the flotation platform 3 move up and down with the surfacewaves without adversely affecting the operation of the surfacecomponents of the system or damaging the cable 53 or hose 5. As anadditional safety precaution to prevent damage to the draft hose 5 fromoverstretching, the arrangement of FIG. 7 includes the short length orsection (e.g., 5 feet) of cable 53′. This safety cable 53′ asillustrated is attached between the top of the spring 59 and the inlet7. In use as best illustrated in FIG. 10, the safety cable 53′ willlimit the maximum distance (e.g., 5 feet) the spring 59 and hose 5 willbe stretched by a surface wave lifting the flotation platform 3. Thespring 59 but more importantly the hose 5 will then not be overstretchedand damaged beyond design limits. With the above features, the system 1can be safely used in relatively large bodies of water where manydifferent depth settings are needed (both initially and fromseason-to-season as drought and other conditions may vary the waterdepths). It can also be safely used in bodies of water where relativelylarge waves may be generated by the wind or other factors such asrecreational boats.

It is noted that the hose 5 is described above as being about 26 feet inlength in the discussed embodiments. This is a length that serves manyexisting bodies of water; however, the hose could certainly be longer(e.g., 80-100 feet or more) or made up of sections or multiples of 26foot hoses such as hose 5. As for example, a series of such 26 foothoses 5 could be secured to one another by housings such as 25 to extend104 feet or more down with the inlet 7 then on the bottom section. Thesections would still preferably collapse to a relatively short height(e.g., 16 feet in this example) for ease of handling and shipping.

FIG. 11 schematically illustrates the circulation system 1 of thepresent invention adapted to include an eutrophication control system71. In this regard, many lakes and wastewater reservoirs have excessdissolved phosphate which can lead to eutrophication. This is acondition where harmful algae blooms occur that can lead to lowdissolved oxygen, fish kills, taste and odor in drinking waterreservoirs, and other water quality problems. An estimated 60 percent ofthe reservoirs and lakes in the United States have such excess phosphateaccumulations.

Phosphate is a highly polar molecule, with a positive (+) charge at oneend and a negative (−) charge at the other end. It is believed thatmolecules like phosphate, when dissolved in water, become tightlysurrounded by a sheath of water molecules since water molecules are alsohighly polar. The same thing is thought to occur with calcium hardnessin water in which the calcium also becomes surrounded by a sheath ofwater molecules. In the case of calcium, it has been shown that if thesesheaths of water are broken up (e.g., by magnetic fields as by putting apermanent or electromagnet around a pipe of flowing water or by passinga current through the water as by electrolysis or even sonic orultrasonic waves), the calcium in the water has more exposed surfacearea and thus becomes more reactive. Small particles of calcium willthen accumulate by surface attraction to each other forming relativelylarge clumps of calcium precipitate which will settle out of the water

It has been known for some time that if phosphate and calcium are bothpresent in water, and if the water is mixed, the two will combine in asurface-bonding manner to form a mineral called apatite. The apatitewill then settle out to the bottom of the reservoir and will not easilygo back into solution. It has also been demonstrated that slow mixing ofalgae-laden water aids the apatite formation process, probably due tomolecular charges that exist on the biological film-type coating of thealgae cells. However, the complete process is not well understood.

In the present invention of FIG. 11, a generator 71 has been added tothe basic system 1 of FIGS. 1-10 to impart energy to the uplifted water(e.g., by generating a magnetic field, electric current (AC or DC), orsonic or ultrasonic waves across the flow). Preferably, the generator 71is solar powered. The energy imparting generator 71 serves to break upthe water sheaths surrounding both calcium and phosphate molecules sothat they can more readily combine and form apatite. In this manner, thecalcium normally present in abundance in ponds, lakes, reservoirs, andother bodies of water can be used to effectively reduce and precipitateout undesirable amounts of phosphate that may be in solution in thewater.

FIG. 12 schematically illustrates another set of embodiments 1′ of thepresent invention that are highly desirable in treating and processingbodies of water such as municipal wastewater ponds 4′. In suchwastewater ponds 4′, it is essential to establish an upper zone 20 foraerobic digestion using dissolved oxygen and a lower zone 22 withvirtually no dissolved oxygen for anaerobic digestion of materials suchas some organic wastes and chemical compounds. The ponds 4′ themselvesare typically 5 to 15 feet deep and the zones 20 and 22 are commonlyabout 2 feet each. Each zone 20 and 22 performs different but vitalfunctions in the overall treatment and processing of the wastewater.Further, to be effective, the contents of the two zones 20,22 must beessentially isolated from one another. Yet, at the same time and forbest overall results in the treatment and processing of the entire pond4′, it is desirable to have a small quantity of the contents of thelower zone 22 brought up and mixed with the contents of the upper zone20.

To accomplish this, conventional aerators and circulation systems aswell as the circulating system 1 in FIGS. 1-11 are very difficult toeffectively use in the environment of a wastewater pond such as 4′. Thefundamental problem is that such systems as 1 are primarily intended tocreate an overall flow 24 (see Schematic FIGS. 13 and 14) in the body ofwater 4′ circulating from the bottom or inlet 7 of the draft tube 5 upto the surface 6, out to the water edges, and back down to the level ofthe tube inlet 7. In this light and if the tube inlet 7 is set too deepas schematically shown in FIG. 13, it will mix the entire pond 4′. Indoing so, it will bring up large quantities of sulfides and low pH(e.g., 6) water from the bottom region of the pond 4′, which willnormally kill the desirable aerobic bacteria and algae of the higher pH(7.5) upper region. Such overall pond circulation 24 in FIG. 13 willalso drive dissolved oxygen from the upper region of the pond 4′ downinto the lower region, which will kill the desirable methane forming andother bacteria necessary to prevent sludge buildup in the bottom layers26 and 28. Odors then develop in the pond 4′ of FIG. 13 due to thepulling up the sludge and there is no upper zone 20 as in FIG. 12conducive to eliminating it as well as reducing the ammonia andprecipitating out any phosphorous. Conversely to being set too deep, ifthe tube inlet 7 is set too shallow as in FIG. 14, a short circuit isdeveloped where the incoming influent 30 from inlet 30′ will essentiallypass untreated through the pond 4′ and out the effluent pipe 32′.

To set the depth of the tube inlet 7 in the systems of FIGS. 13 and 14between these extremes is virtually impossible in the dynamicenvironment of wastewater ponds such as 4′. Among other things, suchponds 4′ have changing overall depths depending upon the volume ofinfluent 30 and effluent 32 as well as varying depth thermoclines andtemperature gradients. The changing of the overall depth of the pond 4′has the effect of raising and lowering the surface level 6 and thus thelevel of the tube inlet 7 depending from the flotation platform.Thermoclines and temperature gradients in the pond 4′ can also operateto effectively change the desirable level to set the tube inlet 7. Asfor example, the influent 30 typically enters the pond 4′ (e.g., one ortwo feet above the sludge layer 26) at a different temperature (e.g., 1to 20 degrees F. lower in the summer) than the pond water above it. Athermocline or gradient can then be created across the pond 4′. As thetemperature difference varies over time (days or seasons) and/or thevolume of the influent 30 and effluent 32 varies, the thermocline mayrise or fall changing the desired level for setting the inlet 7. Too lowa setting of the tube inlet 7 as discussed above will create theundesirable conditions of FIG. 13 and too high a setting will result inthe undesirable conditions of FIG. 14.

To solve these problems, the embodiments 1′ of FIGS. 12 and 15-22 weredeveloped. With them, a circulating aerobic flow F (FIG. 12) in theupper zone 20 is created and limited to the upper 2 feet or so of thepond 4′. Additionally, a small volume of the contents of the loweranaerobic zone 22 is brought up and mixed into the circulating flow F ofthe upper aerobic zone 20. However, the zones 20 and 22 are essentiallyotherwise isolated from each other. In particular, no harmful dissolvedoxygen from the upper aerobic zone 20 is driven down and mixed into thelower anaerobic zone 22, which would destroy the beneficial methaneforming and other bacteria of the lower zone 22. Further, variations inthe overall depth of the pond 4′ over time and varying thermoclines andtemperature gradients created over time in the pond 4′ largely do notaffect the efficient operation of the embodiments 1′. This is the casebecause the embodiments 1′ are essentially independent of such factors.

As indicated above, certain of the contents (e.g., sulfides) of thelower zone 22 can be detrimental to the desirable bacteria and algae ofthe upper zone 20. However, the bringing up of a very small volume ofthese contents as well as other contents can be beneficial to theoverall treatment and processing of the wastewater in the pond 4′. Morespecifically, the lower zone 22 does have nutrients (e.g., carbon,nitrogen, and phosphorous) beneficial to a strong algae crop or growth.In particular, carbon from the lower zone 22 in the form of carbonicacid is very desirable to bring up to the upper zone 20 to nourish thealgae. A strong algae crop in turn raises the pH of the upper zone 20(e.g., to a level of 7.5 to 10). The elevated pH helps to process theliquid ammonium ions being brought up from the lower zone 22 throughnitrification. Additionally, at the higher pH ranges (e.g., over 9.2pH), virtually all of the liquid ammonium ions will be converted intoammonia gas and harmlessly dissipated or gassed off into the atmosphere.Heavy algae growth in zone 20 provides increased surface area forattachment of beneficial nitrifier bacteria needed for the nitrificationand denitrification process of ammonia removal. Further, the higher pH'sin the upper zone 20 help to precipitate out calcium hardness.

The upper zone 20 and its algae growth are normally limited to the first2 feet or so of the pond 4′ This is due in part to natural factors(e.g., sunlight typically is greatly diffused at depths greater than 2feet in such ponds 4′). It is also due to the mechanical operation ofthe embodiments 1′ which serve to confine and substantially limit thecirculating flow F in FIGS. 12 and 19 to about 2 feet. Further, and inaddition to the movement of the circulating flow F physically limitingany descent of the algae growth below 2 feet, a thermocline is establishat the level of the plate member 46 (as explained in more detail below)to inhibit any decent of the algae below it. Algae is then not mixedbelow the level of the plate member 46 (e.g., 2 feet) in normal windsand other operating conditions. In this way, little if any algae passesdown and out of the effluent pipe 32′ in FIG. 12 in violation ofgovernmental and other guidelines on the amount of such biochemicaloxygen demand materials that can be present in the discharging effluent32.

Referring to FIGS. 15-18, the embodiments 1′ of the present inventionare specifically designed for the environment of wastewater ponds 4′ butpreferably have many of the same parts as the embodiments of FIGS. 1-11.As for example, the flotation platform 3 (FIG. 15) is essentially thesame as well as the dish 19, impeller 21, and housing 25. Also like theearlier embodiments 1, the embodiments 1′ have a draft tube 5′ butunlike the earlier embodiments 1′, the draft tube 5′ has an overallJ-shape. The draft tube 5′ is also designed to rest in theweight-bearing layer 28 of the sludge with the inlet 7′ positionedslightly above (e.g., 1 foot) the slurry or non-weight bearing layer 26.In this regard, the bottom curve or bend in the main body 34 of thedraft tube 5′ in FIG. 15 can be provided with a bar or other weight 36(see FIGS. 16 and 16 a) secured in place by screws or other members 38.The main body 34 of the tube 5′ then rests as illustrated in FIG. 15 inthe weight-bearing layer 28 (e.g., capable of supporting 0.25 pounds persquare inch) with the inlet portion 7′ positioned as shown. The inletportion 7′ is preferably buoyant (e.g., by providing styrofoam floatingballs in it). The exact location of the holes 40 in the inlet 7′ canvary relative to the sludge layers 26 and 28 and the exact upper limitsof the anaerobic zone 22 but ideally, at least the lower set of holes 40are in the anaerobic zone 22. In any event, the resulting water beingdrawn through the holes 40 into the draft tube 5′ will predominantly becomponents of the anaerobic materials of the lower zone 22. The weight36 preferably then anchors the draft tube 5′ in the sludge layers 26, 28even if the flotation platform 3 drifts on the surface 6 to one side orthe other. In doing so, the main body 34 of the relatively rigid, fixedlength (e.g., 20 feet) tube 5′ essentially lays somewhat on its side,descending at a slant or incline to the vertical (see FIG. 16 which is aview taken along line 16-16 of FIG. 15).

Referring again to FIGS. 15-18 and although the flotation platform 3,dish 19, impeller 21, and housing 25 are substantially the same as theembodiments 1 of FIGS. 1-11, the embodiments 1′ for the wastewater ponds4′ have a modified supporting arrangement for the draft tube 5′. Morespecifically, the draft tube 5 of the earlier high flow embodiments 1had the upper rim thereof (see FIG. 4) secured at 39 about the flange37. Consequently, preferably all of the water fed to the impeller 21came from the bottom of the pond 4 up through the draft tube 5. Incontrast, the outlet portion 42 (FIG. 15) of the modified tube 5′ issupported to feed only a small amount of the total water input fed tothe impeller 21. This can be accomplished in a number of ways. As forexample, the substantially cylindrical outlet portion 42 of the tube 5passing up through the central opening in the plate member 46 as seen inFIGS. 15 and 17-19 preferably extends outwardly of the vertical axis 44(FIG. 15) for a distance (e.g., 0.5 feet) less than the distance (e.g.,1.5 feet) the housing 25 so extends. Further, the supporting arrangementfor the tube 5′ includes this horizontally extending plate member 46(see FIGS. 15 and 17-19) which is spaced vertically from and below theimpeller housing 25. An inlet opening extending substantially about thevertical axis 44 is thus created therebetween leading to the impeller21. Additionally, the plate member 46 extends outwardly of the verticalaxis 44 (FIG. 19) for a distance (e.g., 2 feet) preferably greater thanthe distance (e.g., 1 foot) the annular housing 25 extends.Consequently, in operation, the impeller 21 draws a first volume ofwater 48 in FIG. 19 horizontally above the plate member 46. In doing so,a portion 48′ (e.g., 30%) of the total volume of drawn water 48 (e.g.,total of 10,000 gallons per minute) passes through the impeller 21toward the surface 6 from the inlet opening between the plate member 46and the housing 25. This portion 48′ passes up and over the dish 19 at12 as well as out the annular opening between the dish 19 and housing 25at 10. This movement of the portion 48′ in turn induces the remainingportion 48″ (70%) of the first volume 48 to move upwardly about thehousing 25. The circulating flow F (see also FIG. 12) is thus createdand essentially defines the upper aerobic zone 20.

To this circulating flow F in the zone 20, a second, smaller volume 52(see FIG. 19) is added which has been drawn up by the impeller 21through the tube 5′ from the lower zone 22. The second volume of water52 drawn up through the tube 5′ is preferably only a small fraction(e.g., 1/100 to ⅕) of the first volume 48. In this manner, the desiredaerobic nature of the upper zone 20 is not adversely affected yetvaluable reduction of some of the contents (e.g., ammonia and phosphate)of the lower zone 22 is performed adding to the overall treatment andprocessing of the wastewater pond 4′. Further, as discussed above, somebeneficial contents (e.g., carbonic acid) are also brought up to nourishthe desirable algae growth in the upper zone 20.

In any event, the second volume 52 allowed to be drawn up must be keptto a relatively small fraction of the circulating flow F so as not toadversely affect the aerobic makeup of the upper zone 20. This can bedone in any number of ways. If the characteristics of the particularpond 4′ are well known and defined, the diameter of the tube 5′ can beselected as desired with a smaller or larger diameter resulting in moreor less frictional drag to the flow of the second volume 52. A smallerdiameter would thus create more drag and reduce the size of the secondvolume 52. The tube 5′ can also be provided with a valve mechanism(e.g., gate valve 54 in FIGS. 18 and 20) to control and adjust the sizeof the second volume 52. The planar plate member 46 can also beadjustably supported to the flange 56 of the housing 25 by a bolt andnut arrangement 58 and 60 (see FIGS. 18, 20, and 21). In a mannersimilar to the operation of members 43 and 45 in FIG. 7, the distancebetween the plate member 46 and housing 25 can be varied by rotating thethreaded bolts 58 in FIGS. 18, 20, and 21 to alter the size of the inletopening between the plate member 46 and housing 25. Such movement willalso vary the space between the end 62 (FIG. 21) of the outlet portion42 of the tube 5′ and the impeller 21 and housing 25. The spacing of theend 62 of the outlet portion 42 can also be separately adjusted byproviding a concentric, sliding member 42′ on the fixed member 42″ ofthe outlet 42 in FIG. 21. The input through the inlet portion 7′ couldalso be valved in similar manners. Regardless of the manner ofadjustment, the absolute and relative sizes of the first and secondvolumes 48 and 52 are preferably variable as needed and desired.

Another advantage of the adjusting techniques for the first and secondvolumes 48,52 is that essentially the same basic units 1′ can be used ina series of wastewater ponds (see FIG. 22). In such a series, it isusually desirable to vary the fraction of the second volume 52. It isalso normally the case that the influent 30 entering the first pond isthe strongest and most concentrated wherein it is desirable to draw uponly a very small fraction ( 1/60). The treated effluent leaving thefirst pond and entering the second pond would then be less concentratedand a larger fraction (e.g., 1/40) could be drawn up the tube 5′. Thefraction in the third pond could then be even larger (e.g., 1/20) andthe final still larger (e.g., ⅕). The water passing through the seriesof ponds and exiting at 32 would then be progressively and efficientlytreated.

The fraction (e.g., 1/60) set for the first pond in FIG. 22 can bevaried as discussed above. In doing so, the operating results of thepond can be monitored and adjustments made in the field if necessary.For an initial setting, however, the conditions of the pond can also bestudied. As for example and in a pond with a surface area of about 5acres, the upper and lower zones 20,22 may be considered as respectiveblocks of 1,000,000 pounds of water each. The lower zone 22 in summermight be mostly raw sewage with about 220 pounds per million ofbiochemical oxygen demand materials. The 220 pounds of material of thelower zone 22 would then need about 1.5 pounds of dissolved oxygen forfast odorless aerobic digestion. The lower zone 22 might also typicallycontain 30 pounds per million of liquid ammonium ions. Each pound ofammonium ions would then need about 5 pounds of dissolved oxygen to gothrough nitrification and eventually denitrification and conversion tonitrogen gas that can be released to the atmosphere. The totalrequirement of the lower zone 22 materials would thus be about 480pounds of dissolved oxygen to aerobically treat the biochemical oxygendemand and liquid ammonium ions (i.e., 220 times 1.5 plus 30 times 5).However, the top block of water in zone 20, even at full saturation,typically holds only about 8 pounds per million of dissolved oxygen. Soto mix the bottom water with the top and keep all of the dissolvedoxygen needs satisfied, a desired mixing fraction is about 60 parts oftop water with every 1 part of bottom water. A 60:1 ratio would then bean anticipated setting for such a pond in order not to deplete thedissolved oxygen content of the upper zone 20. On a volume comparison,approximately 160 gallons per minute would be brought up from the lowerzone 22 to be mixed with the water of the upper zone circulating atabout 10,000 gallons per minute.

It is noted that the various valving and other arrangements foradjusting the size of the volume 52 being drawn up the draft tube 5′could be automated if desired. As for example, a probe or sensor 16 (seeFIG. 15) could be provided to monitor the amount of dissolved oxygen inthe zone 20. The electronic actuator 54′ for the valve 54 in FIG. 18could then be connected by line 18 to the sensor 16. In operation, theactuator 54′ would be automatically activated in response to readingsfrom the sensor 16 to selectively move the valve 54 to adjust the sizeof the volume 52. If the dissolved oxygen readings are relatively high,the volume 52 could be increased. Conversely, if the readings fall tolevels threatening the vitality of the zone 20, the volume 52 can bedecreased or even shut off completely. In this regard, all of thevarious arrangements for adjusting the size of the volume 52 could be soautomated.

Referring again to FIG. 1 and in the environment of the first set ofembodiments 1 in the ponds 4 with full pond circulation, it is normallydesirable to limit the incoming flow to the tube inlet 7 in FIG. 1 to asubstantially horizontal flow 66. Preferably, no water is drawn upwardlypast the solid planar member 70 of FIG. 1. In this manner, many of theworst contents of the pond 4 (which typically settle to the pond bottom)are not disturbed and not drawn up and circulated to contaminate therest of the pond 4. However, in some environments such as the tidalcanal 4″ of FIG. 24, it is desirable to be able to draw up some of thecontents 68 below the plate member 70. More specifically and in a canalor similar body of water such as 4″, the situation can develop thatdeadly sulfides from fish waste and other organic waste settle andcollect in dangerous amounts at the bottom 26 of the canal 4″. This isbecoming very common in many canals that may be 100 feet wide withnormal 6 foot deep sides but with a central, dredged depression 50 wideand 20 feet deep. Under most conditions during a year, the sulfides areconfined and remain at the bottom 26. However, during certain times ofthe year (e.g., summer) and/or during certain catastrophic events (e.g.,big storms or floods), the deadly sulfides can be displaced and/or mixedupwardly into the canal 4″. The results can be devastating, includingkilling virtually all of the fish and other animal life in the canal 4″.Such fish and other kills from contact with the deadly sulfides areinfrequent events but can destroy the vitality of a canal or similarbody of water 4″ in simply a matter of days or even hours.

Consequently, in the environment of a body of water like the canal 4″ inFIG. 24, it is desirable to continuously draw small volumes 68 of waterfrom below the plate member 70 of the suspended inlet 7 of the dependingtube 5 (see also FIG. 23). These sulfides normally build up in and abovethe layer 26 in FIG. 24 and below (e.g., 2 feet) the planar plate member70. In operation and over the course of days or months, very smallvolumes of these deadly sulfides are slowly brought up toward the canalsurface and dissipated throughout the canal 4″. In such small volumes(e.g., 2%-10% of the total volume drawn up the tube 5 as for example20-100 gallons per minute of a total draw of 3,000 gallons per minute)and concentrations (e.g., 110 parts per million), the sulfides can beprocessed and broken down (e.g., to sulfates) in the canal 4″ withoutharming the fish and other wildlife.

When a catastrophic or other unusual condition in the canal 4″ occurs,any sulfides at the canal bottom are still raised or stirred up into themain body of the canal 4″. However, their volumes and concentrations aremuch smaller and less toxic due to the prior, cleansing operation of thesystem of FIGS. 23 and 24. Additionally, the volume and rate of sulfidesand other materials being drawn up at 68 through the plate member 70 inFIGS. 23 and 24 are preferably adjustable (e.g., by the sliding valvemember 72). In this manner, the operation of the system can be preciselyadapted to particular environments and changes in the environments ofthe ponds or other bodies of water including 4″. The valve member 72 inFIG. 23 can even be closed completely if desired or needed to strictlylimit the entire flow coming into the tube inlet 7 to the horizontaldirection 66 in FIGS. 1, 23, and 24.

The plate member 70 in this regard extends substantially horizontallyoutwardly of the vertical axis 13 in FIG. 23. The plate member 70 isalso spaced from and below the main body 34 of the draft tube 5 tocreate the substantially annular inlet opening therebetween for theincoming flow 66. Additionally, the operation of an electronic actuator72′ for valve 72 in FIG. 23 could be provided if desired toautomatically adjust the size of the volume 68. Preferably, the sensor16 would monitor hydrogen sulfide adjacent the plate member 70 but itcould also monitor other conditions or be positioned as in FIG. 15 toread dissolved oxygen levels near the surface 6. If the valve 72 is notautomated and the normal tides in the canal 4″ or other body of waterare fairly significant (e.g., 2 to three feet), the opening through theplate member 70 would either be sized or the valve 72 set to bring up asafe amount of sulfides in the volume 68 at low tide. At high tide withthe plate member 70 two or three feet higher, the concentration of thesulfides in the volume 68 would normally be less but sulfides wouldstill be brought up through the plate member 70 for treatment.

In FIGS. 25 and 26, the inlet 7 of the draft tube 5 has been modifiedfor use in bodies of water such as municipal drinking or potable wastertanks 4′″. Such tanks commonly range from 100,000 to 150,000 gallonswith depths from 30 feet when full to 4 feet or less during high oremergency use of the water. The water in the tanks like any other bodiesof water can stratify due to temperature differences. Additionally, thewater can age and become old in some parts of the tank leading to lossof chlorine concentration or residual. Further, if chloramine is used orapplied instead of chlorine, nitrification can occur. Consequently, itis desirable to mix the entire body of water in the tank 4′″. In doingso, the inlet 7 of the draft tube 5 as shown in FIG. 25 has beenmodified to include an arrangement of legs 80 to support the platemember 70 at a predetermined distance just off (e.g., inches to 1 or 2feet) the bottom 82 of the tank 4′″. Normally, this is just above anysediment in the tank 4′″ so as not to unnecessarily disturb and draw itup. Although the plate member 70 can be valved as previously shown, thevalve 72 is preferably closed so as to make the plate member 70 solidand not to bring up any flow from below the member 70. The lengths ofthe legs 80 are adjustable as by threaded bolts 58′ and nuts 60′.Consequently, the distance the plate member 70 is positioned above thebottom 82 of the water can be adjusted as needed or desired. Each legmember 80 contacts the bottom 82 and is individually adjustable, whichcan be advantageous if the bottom 82 of the tank 4′″ is sloped orotherwise irregular and not flat. The leg members 80 in FIG. 25 extenddownwardly of the plate member 70 and are positioned outwardly (e.g., 1to 2 feet) of the plate member 70 for stability.

As mentioned above, the depth of the water in tanks such as 4′″ can varywidely (e.g., 30 to 4 feet or less) depending upon the municipal waterdemands. Correspondingly, the length of the collapsible tube 5 canchange dramatically. In particular and at low levels of water, thebottom of the depending tube 5 may undesirably fold up and fall to oneside or the other of the inlet portion 7 supported on the tank bottom82. This can then adversely affect the overall operation of the system.To help prevent this, an arrangement of three or more arm members 84 isprovided to collect and contain the collapsing tube 5 (see FIG. 26). Thearm members 84 as illustrated extend vertically upwardly from adjacentthe inlet portion 7 of the tube 5 and are preferably evenly spaced aboutthe main body 34 of the tube 5. Consequently, as the main body 34 of thetube 5 collapses as the water level falls, the arm members 84 willcapture or collect and contain the main body 34 of the tube 5 adjacentthe inlet portion 7. The arm members 84 then keep the tube 5 fromundesirably falling to one side or the other of the inlet portion 7 atthe bottom 82 of the tank 4′″.

FIG. 27 illustrates an adaptation of the present invention to thespecific environment in which the contents of the pond 4′ or other bodyof water are intended to remain in place for a relatively long period oftime. Such ponds 4′ for example might be used to treat strong wastesfrom meat, vegetable, and paper processing plants as well as wasteactivated sludge from municipal mechanical wastewater treatment plants.In such ponds 4′, it is desirable to let the waste settle to the bottomof the pond 4′ to be anaerobically treated (or just stored) for days,months, or years. In such cases, odor control can be paramount as gasesfrom sulfides and other materials bubble up to the surface 6 and escapeinto the atmosphere.

In such environments, the basic circulating structure creating theaerobic zone 20 in the embodiments 1′ (e.g., FIGS. 15-19) can be veryeffectively employed to create an odor cap for the pond 4′ of FIG. 27.In particular and with the plate member 46 of the embodiments of FIGS.15-19 closed or otherwise made into a solid piece and creating thecirculating flow F as in FIG. 27, the contents of the pond 4′ below thelevel of the plate member 46 will be essentially isolated and preventedfrom reaching the surface. Further, any gases bubbling up into the zone20 from below the level of the plate member 46 will be effectivelytreated in the aerobic environment of zone 20 and harmlessly releasedinto the atmosphere. Preferably, the operation of the dish 19 (see FIG.19) would still be substantially the same in the environment of FIG. 27,whether or not the plate member 46 of FIG. 19 is solid or the flowthrough the draft tube 5′ is simply closed to effectively make themember 46 a solid piece. The flow 48′ from the depths (e.g., 1 to 2feet) of the pond 4′ passing through the housing 25 would then beproportioned as in the earlier embodiments 1 to flow along paths 10 and12 in FIG. 19.

While several embodiments of the present invention have been shown anddescribed in detail, it to be understood that various changes andmodifications could be made without departing from the scope of theinvention.

1. A water circulation system for drawing water from the depths of abody of water to the surface for exposure to the atmosphere and creatinga circulation pattern in the body of water, said system including aflotation platform, a dish supported slightly below said surface, adraft tube having upper and lower end portions wherein the draft tube iscollapsible and the length thereof adjustable to vary the depth of thelower end portion of the draft tube in the water, and an impeller todraw water from the depths of said body of water up through said drafttube to the surface of the body of water wherein said system includes aspring positioned within said draft tube substantially closer to thelower end portion thereof than to the upper end portion thereof toabsorb the force of surface waves raising the flotation platform.
 2. Thesystem of claim 1 wherein said system further includes a cable sectionto limit the expansion of the spring.
 3. The system of claim 1 whereinsaid system further includes a cable section to prevent the expansion ofthe collapsible draft tube beyond a predetermined limit.
 4. A watercirculation system for drawing water from the depths of a body of waterto the surface for exposure to the atmosphere and creating a circulationpattern in the body of water, said system including a flotationplatform, a dish supported slightly below said surface, an impeller, anda draft tube having upper and lower end portions wherein the draft tubeis collapsible and the length thereof adjustable to vary the depth ofthe lower end portion of the draft tube in the water wherein thecollapsible draft tube is constructed to be substantially neutrallybuoyant separate from the flotation platform, dish, and impeller.
 5. Thesystem of claim 1 wherein the spring is substantially at the lower endportion of said draft tube.
 6. The system of claim 2 wherein the springis a coil spring and said cable section extends downwardly within saidcoil spring.